Continuous pressurized impregnator type pulping digester



April 27, 1965 sHlNoBu FUcHlwAKl 3,180,789

CONTINUOUS PRESSURIZED IMPREGNATOR TYPE PULPING DIGESTER Filed Nov. 16, 1962 INVENTOR. SH/NOBU Fl/(HIWAKI ATToRNEYS United States Patent O This invention relates to improvements in a continuous Y pressurized impregnator type pulping digester.

One object of this invention is to provide a pulping digester f the kind described, in which an impregnating time for a liquid chemical is shortened.

Another object of this invention is to provide a pulping digester, in which it is possible to minimize a loss of the liquid chemical by means of providing a density gradient of the liquid chemical corresponding to progress of the impregnation of the liquid chemical intoV chips within a tubular impregnator and further selecting a ratioof quantity of fresh liquid chemical to be supplied to the chips.

Briefly stated in accordance with one aspect of this invention, there is provided a continuous pressurized impregnator type pulping digester having a continuous pressurized impregnator in which chips are impregnated continuously with a liquid chemical under pressure, said impregnator comprising a rotary chip feeder and a rotary discharger, said chips being fed into said impregnator through said rotary chip feeder and discharged out of said impregnator through said rotary discharger whereby said impregator is kept in such a condition that there is a density gradient of said liquid chemical.

The invention will be better understood andfother objects and additional advantages of the invention will become apparent upon perusal of the following description taken in connection withv the drawings, in which:

FIG. 1 is a flow sheet of a pulping digester in accordance with this invention;

FIG. 2 is a vertically sectional side view of a rotary a rotary discharger 12. Theirotary chipfeeder 11 is` provided with a casing body 21. The casing body 21 is provided with a chip inlet 27 and a chip outlet 28 arranged radially in alignment to the former. The casing body 21 is providedY also with an inlet passage 60 and an outlet passage 61 Varrangedradially in alignment to the former. The chip inlet 27 and the chip outlet 28 are` arranged radially out of alignment to the inlet passage 6i) and the outlet passage 61. A rotor 22 is provided in close itting proximity to a liner 29 provided inside the casing body 21, and has two passageways 23 and 24. Each of these passageways 23 and 24 is arranged so as to place in communication the chip inlet 27 and the chip outlet 28 with the inlet .passage 60 and the outlet passage 61, respectively, as shown in FIGS. 2 and 3 upon rotation of said rotor, but it is impossible to connect the chip v inlet 27 and the chip outlet 28 with'the outlet passage 61.V

and the inlet passage 60, respectively. Two strainers 25 and 26 are provided at one of the ends of the passageways There is a hopper 31 which is fed with chips by means of a chip conveyor 30. A chip chute 34 is charged With the chips through a chip meter 32 and a screw conveyor 33. The chip chute 34 is also charged with chemical liquid. In operation, the pressure inside the chip outlet 28 is kept higher than the inside of the chip inlet 27.- When the rotor 22 is rotated, some quantity of chemical liquid leaks into the chip inlet 27 through the clearance between the rotor 22 and the liner 29. Such leak is directed into the chip chute 34 as above and mixed with the t chip Vso as to suspend the chips in the liquid with the level of the liquid being kept constant by means of an overow pipe 35. When the passageways 24 are in communication with the chip inlet 27 and the inlet passage 69, the liquid carrying the chips within the chip chute 34 is directed to the passageways 24 through the chip inlet 27 and so as to recirculate the liquid from the inlet passage, a

'recirculating pump 36 and a tlOw indicator are used to force the liquid back to said chip chute. Thus the chips are left Within the pocket 24 by virtue of the strainer 26. At the same time, chips which have been left within the other passageway 23 is forced to leave the passageways 23 into the chip outlet 28 together with and by liquid supplied from a recirculating pump 37, whence the liquid is directed to the tubular impregnator 33 together with the chips.

A similarly constructed chip discharger 12 is provided at the exhaust side of the tubular impregnator 38 which is operated without any recirculating pump.

The chips with which the tubular 'impregnator 38 is charged are .carried by screw conveyors towards the chip discharger 12, being impregnated with the liquid under pressure. The chips discharged through the chip discharger 12 are directed to a live bottom bin 39 and stored within it together with the liquid exhausted and leak. Then the chips are Washed by water and directed to a drainer conveyor 42 through screw conveyors 40 and 41. Then the chips are further washed and drained and supplied to a primary rener 43. The chips now to be called pulp are roughly crushed and distributed to secondary reners 46 uniformly by means of a kdistributing conveyor 44 anduniflow conveyors 45, where the pulp is further rened. Any excess of the pulp conveyed through the distributlng conveyor 44 is returned to the inlet of the draining conveyor 42. Meantime, the pulp rened by the secondary reiiner`46 is stored in a reflner chest 47 provided with a stirrer 13 for preventing the. pulp from precipitation, so as to provide for the next operation. Waste liquid drained by means of the live bottom bin 59 and the drainer conveyor 42 is stored in a waste pit 48.

Further a liquid recirculating system and a pressurizing system will now be explained. The liquid directed to a level tank 49 through the overflow pipe 35 is heated up to a temperature of about 40 C. by means of a heating coil 50 provided within the tank 49 and returned to the tubular impregnator 3S through a strainerv52 by-'means of a chem1cal pump 5l. In this system, the throughput in vthe chemical pump-51 is to be the same with the throughput in the overflow pipe 35, that is, the leak through the rotarychip feeder 1l. Therefore, the pressure loss derived from the leak through the rotary chip feeder 11 is compensated by returning the liquid through the chemical pump 51. The liquid contained within the tubulartimpregnator 38 is pressurized by a pressure pump S3. The throughput of the pressure pump 53r is controlled by the pressure inside the impregnator 38. Therefore, the throughput of the pressure pumpr53 becomes the same Y with the sum-v of the waste liquid discharged by the rotary discharger 12 and the leak therethrough.

Therefore, itis possible to dilute the liquid within the tubular impregnatorti by making the total quantity of washing water supplied at the live bottom bin 39 and the drainer conveyor 42 same With the quantity of the liquid discharged or making the former more than the latter, by means of the pressure pump 53. In such a manner as above, overflowing the liquid through the overliow pipe 55 gradually, it is possible to substitute washing water for the liquid within this system. In such a condition as above, ow of the liquid is hardly found through a strainer provided within the tubular impregnator 38 and beyond it. Mere influence of the stirrer 13 would be found there. In such a balancing condition of the liquid, when a quantity of fresh liquid chemicals is supplied from the chemical pump 54, a difference of the quantity of the fresh liquid impregnated by the chips from that supplied corresponds to the quantity exhausted through the rotary discharger 12.

The reference numeral 56 represents a chemical tank, numeral 57 represents a liow indicator, numeral 58 represents a flow control valve, numeral 59 represents a pressure control valve, numeral 14 represents a fresh water pipe, and numeral 15 represents a diluting pipe.

While a particular embodiment of this invention has been illustrated and described, modifications thereof will readily occur to those skilled in the art. It should be understood therefore that the invention is not limited to the particular arrangement disclosed but that the appended claim is intended to cover all modifications which do not depart from the true spirit and scope of the invention.

What I claim is:

A continuous pressurized impregnator type' pulping digester comprising a continuous pressurized tubular chip impregnator capable of continuously moving chips through a liquid chemical under pressure and having an inlet and an outlet, a rotary chip feeder having a casing body with a radially extending chip inlet, a chip outlet arranged in alignment with said chip inlet and connected to said impregnator inlet, a radially extending inlet passage means and an outlet passage means arranged in alignment with said inlet passage means, said chip inlet being arranged radially out'of alignment with said inlet passage means and a rotor rotatably mounted in said casing body with space therebetween for the leakage of liquid, said rotor having a pair of passageways each arranged to alternatively place said chip inlet in communication with said outlet passage means and said inlet passage means and said chip outlet in communication with said inlet passage means and said `outlet passage means upon rotation of said rotor, a chip chute connected to said casing body chip inlet, and having an overflow outlet, means for moving the liquid chemical from said casing body outlet passage means to said chip chute, means for moving liquid chemical under pressure from said chip impregnator to said casing body inlet passage means, strainers provided in said rotor passageways and a rotary discharger connected to said impregnator outlet and means for feeding liquid chemical under pressure into said impregnator.

Reffereuces Cited by the Examiner UNITED STATES PATENTS 2,414,062 l/47 Richter 162-237 2,966,215 12/60 Durkee 162-237 3,034,576 5/62 Putnam et al 162-237 3,085,624 4/ 63 Horstman 162-237 FOREIGN PATENTS 710,330 6/54 Great Britain. 128,264 5/50 Sweden.

DONALL H. SYLVESTER, Primary Examiner.

MORRIS O. WOLK, WILLIAM B. KNIGHT,

Examiners. 

